iDefense Security Advisory 04.12.11
http://labs.idefense.com/intelligence/vulnerabilities/
Apr 12, 2011

I. BACKGROUND

Excel is the spreadsheet application included with Microsoft Corp.'s
Office productivity software suite. More information is available at
the following website:

http://office.microsoft.com/excel/

II. DESCRIPTION

Remote exploitation of a memory corruption vulnerability in Microsoft
Corp.'s Excel could allow an attacker to execute arbitrary code with
the privileges of the current user.

The vulnerability occurs when Excel parses a specially crafted Excel
file. Specific values within this file can trigger a memory corruption
vulnerability and may allow arbitrary code execution.

III. ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary
code with the privileges of the user opening the file. To exploit this
vulnerability, an attacker needs to convince a user to open a malicious
file. Attackers typically accomplish this by e-mailing a targeted user
the file or hosting the file on a Web page.

IV. DETECTION

The following Microsoft products are vulnerable: <ul> <li> Excel 2002
SP3</li> <li> Excel 2002 SP3</li> <li> Excel 2003 SP3</li> <li> Office
2004 for Mac</li> <li> Office 2008 for Mac</li> <li> Open XML File
Format Converter for Mac </li> </ul>

V. WORKAROUND

The vulnerability occurs in the core parsing code of Excel, and this
code can not be disabled; however, it is possible to disable the
opening of the older binary format files and use MOICE to convert the
file to the newer XML-based format.

VI. VENDOR RESPONSE

Microsoft Corp. has released patches which address this issue.
Information about downloadable vendor updates can be found by clicking
on the URLs shown.

http://www.microsoft.com/technet/security/bulletin/ms11-021.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2011-0103 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

09/09/2010  Initial Vendor Notification
09/09/2010  Initial Vendor Reply
04/12/2011  Coordinated Public Disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2011 Verisign

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
 There are no warranties with regard to this information. Neither the
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